The Shell-Collector’s Handbook. 63 
HYDROBIA SIMILIS, DRAPARNAUD. 
SHELL ovoid, swollen, sub-opaque, pale horn-coloured ; 
whorls five to six, very convex; sutures very deep and 
grooved; umbilicus represented by a narrow and oblique 
chink; mouth oval; operculum horny, concentric, with 
the nucleus lateral. Animal dark grey, tinted with yellow 
or brown, and speckled with flaky white. 
Habitat.—In ditches between Greenwich and Woolwich 
which are flooded by the tide. 
HYDROBIA VENTROSA, MONTAGU. 
SHELL forming a lengthened cone, yellowish horn-coloured, 
thin, glossy, semi-transparent; whorls six to seven, 
swollen ; spire long ; suture not channelled as in H. similis; 
mouth oval; umbilicus smaller than in H. similis. 
Size half that of H. similis. Animal dark grey with black 
and grey rings round the tentacles. 
Habitant.—In estuaries and in brackish water, or upon - 
the mud banks of tidal rivers. 
v. minor (Jeff.): Shell smaller, spire shorter. 
v. decollata (Jeff:): Shell slightly eroded; spire 
truncate. 
v. ovata (Jeff.): Shell having a much shorter spire, 
consisting of only four whorls, which are more swollen 
than usual, and the last considerably exceeds one-half of 
the shell. 
v. elongata (Jeff.): Shell having its spire propor- 
tionally longer, with sometimes as many as eight whorls. 
v. pellucida (Jeff.): Shell clear white, nearly trans- 
parent. 
